21309295447 has 4 divisors (see below), whose sum is σ = 23246504136. Its totient is φ = 19372086760.

The previous prime is 21309295429. The next prime is 21309295481. The reversal of 21309295447 is 74459290312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21309295447 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21309295397 and 21309295406.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21309295247) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 968604328 + ... + 968604349.

It is an arithmetic number, because the mean of its divisors is an integer number (5811626034).

Almost surely, 2^21309295447 is an apocalyptic number.

21309295447 is a deficient number, since it is larger than the sum of its proper divisors (1937208689).

21309295447 is a wasteful number, since it uses less digits than its factorization.

21309295447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1937208688.

The product of its (nonzero) digits is 544320, while the sum is 46.

The spelling of 21309295447 in words is "twenty-one billion, three hundred nine million, two hundred ninety-five thousand, four hundred forty-seven".